MS360 Pro Build

[Lholzen]

Hello, my name is Lucas and I'm 20. I'm new here and this is my first post. I worked as an arborist in high school for a friend but decided to get out of it after I watched a coworker almost get killed. I still love saws though. My uncle is a logger and gave me an older MS360 pro and I want to get a piston to replace the stock one so it can make higher compression. I want to run high-octane fuel and get more power out since I love the saw. I love the saw but it needs more torque. I've built saws and done port work before but I'd rather get a bigger piston for this one—any ideas as to where I might find one the use?

I believe stock it has a 9.6-1 compression at 120 psi but I'd like it to be 11-1 or somewhere near there so I can run 105 or 110 octane drag racing fuel, methanol, or even a nitromethane/methanol blend. It has a 48mm cylinder and piston.

I'm new to this side of saw building so if there's anything I need to know please say it. I have no pride coming into this and I'm very excited to learn more about this.

Thank you everyone!

 

[thompsoncustom]

Chainsaw even new ones are vary low compression ratio but stock cylinder compression should be around 150psi. Even if you have the cylinder machined to up your compression to say 200psi I doubt you would need to more than 87 octane.

What you need to do is talk to someone that does machine work on these and have the band and base cut, also running a bigger piston/cylinder will give you roughly the same compression but will increase your displacement.

What kind of saw are you wanting to build? Work saw or race saw? Figure out what you want out of your saw and everyone here will help you with what you need to do to build it.

 

[spuldup]

On my early 360Pro I used a Hyway pop up piston and sanded (yes, no lathe!) the bottom of the cylinder to get the squish about .018" if i recall. I lunged and roughed the intake, and widened the exhaust and gasket a bit. Did not change timing numbers. Bolted on a eagan muffler. Plugged decomp. It really rips. It is only a little slower than my 038mag.

That said, it is not the best saw to go for high compression. The combustion chamber is large so without filling that area or cutting the squish band and cylinder deck idk if you can benefit from the drag fuel. I believe an 034 head is better suited for that, but won't punch above my weight class to say for sure.

 

[Lholzen]

Chainsaw even new ones are vary low compression ratio but stock cylinder compression should be around 150psi. Even if you have the cylinder machined to up your compression to say 200psi I doubt you would need to more than 87 octane.

What you need to do is talk to someone that does machine work on these and have the band and base cut, also running a bigger piston/cylinder will give you roughly the same compression but will increase your displacement.

What kind of saw are you wanting to build? Work saw or race saw? Figure out what you want out of your saw and everyone here will help you with what you need to do to build it.

I want to build one that can do both, my uncle drag races and has plenty of fuel I'm welcome to use it. I don't see drag fuel conversions often with chainsaws. It's something I'd like to try, practical or not.

 

[Lightning Performance]

I want to build one that can do both, my uncle drag races and has plenty of fuel I'm welcome to use it. I don't see drag fuel conversions often with chainsaws. It's something I'd like to try, practical or not.

The power isn't in the fuel unless you get serious about huge intake setups on methanol or start dipping into nitro on the heavy side, most won't go there. You will need money to venture here more then most are willing to spend. If your just building for fun amd not a cube or CC class then dive in and enjoy like cart racers do. Jackup the compression to the moon and buid a comparable combustion chamber area. The machine work and transfer ports is where you can spend money to get headed in the right direction. If you like doing your own intake and exhaust have at it if you're going for peak power and not something like a milling saw or long bars all day everyday. I build 46 and 48mm Stihls like this for climbing mostly. 360 is the low compression turd of the 1125 gang. That said it can be greatly improved but the 034S and maybe a nasty 034 will step on it They rev and have a better port layout. Still no replacement for displacement. 034S is best. If you want a popup piston it limits your machine work. Pick your poison before you drink. A lot can be done with the air filters, intake and intake track systems. That I'm not willing to discuss on the web. That is the part you pay for. Timing numbers are easy to get. Figuring out how to arrive at what overall is the deal. Everyone does it a little different. Some methods are easily repeated with a good system of taking durations or timing numbers. The black majic comes from decades of doing things to stuff. Knowing what doesn't work gets you farther down the road.

Don't believe everything you see in videos or read is my best advice. Find the answers yourself and move forward accordingly.

I only do cylinders/heads now or new tools/toys going out. Hundreds of people modify these models. Just decide how deep your pickets are and get a good machinist to do your stuff. I'm available for this model.

 

[thompsoncustom]

I want to build one that can do both, my uncle drag races and has plenty of fuel I'm welcome to use it. I don't see drag fuel conversions often with chainsaws. It's something I'd like to try, practical or not.

well everything is a trade off if you want one that does both it's gonna be at a cost somewhere kind of like your uncle probably doesn't use his drag race cars as daily drivers the compromise between the two would be something like a sports car.

Nitromethane would be the only fuel worth doing but then that's good be a drag race style setup and have to be built around that.

You can have great saws that do both tho i'm not trying to talk you out of that I use a ms660 with a expansion pipe for cutting up big logs and it works great and that's a race style saw so there is room to make them do both.

You have to decided what you want to do first before you build it, say you want to run nitromethane that's gonna change your port timing numbers you use and the carb/intake setup for sure vs if you run a expansion pipe vs just porting and higher compression.

Now could you build a work saw that runs nitromethane? Probably but I'm not sure how long it would last a day maybe? Can you use a expansion pipe on a work saw?? Kind of, for some things but the pipe makes unusable in a lot of areas.

I would stay with a work style saw: up the compression, get better timing numbers, widen ports, open up exhaust, advance your timing.

Some saws are really restricted at the intake side so a bigger carb and higher flowing intake can really improve things.

if you want to get wild and crazy you can look into hybrid saws. can you fit a ms460 or 038 super cylinder (different stroke) on your saw with enough machine work idk.

Another thing that increasing speed is a narrower chain like 3/8lp and so does square grinding the chain cutters.

Lots of options out there and like lightening said everyone goes about it a little different.

 

[AlotL1keVegas]

Check out "Johns Custom Saws" on youtube. He's done some nitrous builds. It'll give you an idea of the amount of work, and general idea of what to expect.

 

[Lholzen]

The power isn't in the fuel unless you get serious about huge intake setups on methanol or start dipping into nitro on the heavy side, most won't go there. You will need money to venture here more then most are willing to spend. If your just building for fun amd not a cube or CC class then dive in and enjoy like cart racers do. Jackup the compression to the moon and buid a comparable combustion chamber area. The machine work and transfer ports is where you can spend money to get headed in the right direction. If you like doing your own intake and exhaust have at it if you're going for peak power and not something like a milling saw or long bars all day everyday. I build 46 and 48mm Stihls like this for climbing mostly. 360 is the low compression turd of the 1125 gang. That said it can be greatly improved but the 034S and maybe a nasty 034 will step on it They rev and have a better port layout. Still no replacement for displacement. 034S is best. If you want a popup piston it limits your machine work. Pick your poison before you drink. A lot can be done with the air filters, intake and intake track systems. That I'm not willing to discuss on the web. That is the part you pay for. Timing numbers are easy to get. Figuring out how to arrive at what overall is the deal. Everyone does it a little different. Some methods are easily repeated with a good system of taking durations or timing numbers. The black majic comes from decades of doing things to stuff. Knowing what doesn't work gets you farther down the road.

Don't believe everything you see in videos or read is my best advice. Find the answers yourself and move forward accordingly.

I only do cylinders/heads now or new tools/toys going out. Hundreds of people modify these models. Just decide how deep your pickets are and get a good machinist to do your stuff. I'm available for this model.

Would you happen to know a larger carb that would fit? I want to throw more fuel at it and an old saw builder coworker gave me some tips for easy compression.

Also, if I'm throwing more fuel, that will mean I need a more powerful spark I assume. At least that's necessary on my uncle's drag car. are there any feasible ways to get more spark power without an external battery?

Thank you everyone for helping me, I've learned a lot in just the last few days this post has been up!

 

[Lightning Performance]

Would you happen to know a larger carb that would fit? I want to throw more fuel at it and an old saw builder coworker gave me some tips for easy compression.

Also, if I'm throwing more fuel, that will mean I need a more powerful spark I assume. At least that's necessary on my uncle's drag car. are there any feasible ways to get more spark power without an external battery?

Thank you everyone for helping me, I've learned a lot in just the last few days this post has been up!

No larger carb is a direct fit. Getting something on the studs is your first order of business or change the mounting setup. 1128 044-460 or 1127 029-390 class is bigger but not much. Quite useful if you get through the linkage bits.
Having a choke?
Consider that and how will you prime it if the choke is gone.

Skip running a crank trigger ignition. Your not ready for that yet or the expense. A stock coil will do fine on gasoline. Other fuels might need more spark energy. Don't worry about the ignition system. Run what you have. Ignition lead and plug gap is your current worry. More lead equals more heat just don't burn it down! Less gap increase spark energy but reduces the kernel. Hot spark shouldn't be an issue on gasoline. Get after the intake system and more transfer ports. Bigger is better if you want max rpms and HP.